Letter: Nuclear waste
Your leader referring to the annual report of the Radioactive Waste
Management Advisory Committee pays insufficient attention to the vital dimension
of time (Comment, 24 November). The developments at Drigg now extend its
life for the disposal of low-level radioactive waste well into the next
century. As a result, the current need for the Nirex deep repository is
being driven by the production of intermediate-level waste which, until
the repository is in place, will require the construction of stores above
ground.
Whereas the situation implies that the deep repository could, in the
event, take only intermediate-level waste, this might apply only during
the earlier years of its 50-year life. RWMAC advised Nirex in 1988 that
the repository should not be completed in one phase but should be excavated
further as the need arose. Such an arrangement provides maximum flexibility
for disposal options.
The issue of the disposal of heat-generating waste is very much on the
back burner. Government policy dictates that the vitrified blocks of such
waste will be stored to permit cooling and radioactive decay for at least
50 years. As the very first blocks are only now being produced, disposal
will not take place until before the middle of the next century. In the
meantime, a considerable amount of experience should have been acquired
about the operation and monitoring of deep repositories of different types.
Concern has been raised that the function of the Nirex repository might
be changed to include heat-generating waste sometime well into the future.
Such a proposition would require a government policy decision, a change
in the functions of Nirex (or its successor), and the development of a wholly
new safety case to acquire powers for such disposal.
The consequences of mixing different waste types in the same repository
raises a series of questions and my comment about possible chemical incompatibility
between heat-generating waste and the alkaline environment resulting from
intermediate-level waste disposal was a question rather than a statement.
However, this is an issue that RWMAC will address.
John Knill, chairman RWMAC Shaw-cum-Donnington Berkshire
Letter: Date stamp
I know poets and comedians do not need their facts to be correct, but
archaeologists do, and David Bateman seems to have only half-remembered
the archaeology he studied in Liverpool (‘Half-living in the past’, Forum,
17 November).
The full truth is both less entertaining and more complex and I fear
that here is not the place to recount how the Before Present convention
saves all radiocarbon dates from being changed every time there is an improvement
in the technique. However, the point is that every archaeologist knows that
not only does ‘P’ not mean the present (changing) year, but also that the
date is not even in calendrical years. It is in radiocarbon years, which
are quite different.
The two are related by a calibration curve which has been constructed
for the past 10,000 years. A calendrical date can be read off from this
curve, and is expressed as Cal AD or Cal BC. If radiocarbon dates are being
compared one uses the BP date, while if calendrical dates are under discussion
one uses the Cal date.
It may amuse you that a small error occurred in the calibration curve
until it was realised that to go smoothly from BC to AD calendrical dates
the dates 0 BC or 0 AD do not exist.
R E M Hedges Radiocarbon Accelerator Unit University of Oxford
Letter: Clock-watcher
Reading a British journal while living elsewhere we accept that ‘the
trains’ and ‘the minister of X’ refer to the British variety, that it is
our own problem if we do not understand unexplained acronyms, and that chemical
leaks and holes in the ozone layer are important in proportion to their
proximity to London.
However, I was a bit startled by Michael Cross’s assertion that ‘the
world’ was about to put its clocks back at the end of daylight-saving time
(‘The land of the sticking clock’, Forum, 27 October). Surely there must
be someone on the staff who knows that in the southern hemisphere the cricket
season occupies the other half of the year?
Aileen Keely Blackburn Australia
Low energy
David Olivier claims that energy efficiency could reduce world energy
demand to ‘barely one kilowatt per person for a European standard of living’
(Letters, 17 November). This looks suspiciously like the figure published
in Energy for a Sustainable World. If it is, Olivier omits some important
qualifications.
First, the ESW figure is for Third World consumption only. Even so,
it is artificially low because (among other things) it assumes that the
Third World is uniformly warm so that its inhabitants do not require space
heating – but nor do they use air-conditioning on a significant scale.
Second, the standard of living assumed reflects a mixture of OECD Europe,
Australia, New Zealand and Japan in about 1975: Olivier omits the date.
And third, one kilowatt refers to final energy consumption, so a lot can
be achieved by using electricity as much as possible.
As an example, ESW assumes that domestic hot water is produced by an
electric heat pump. This is more efficient than burning fuel and much more
efficient than using electricity directly. In the latter case, however,
on ESW’s figures the capital cost per kilowatt saved is around $3,500 (1982
dollars), or perhaps 2,500 Pounds in current money. Can this be compared
with the cost per kilowatt of power stations?
If water is heated with off-peak or interruptible electricity the cost
of the generating plant required can be very low. And water-heating is the
sort of load which can usefully be controlled to balance a system fed from
unreliable renewable resources. Simple calculations of cost per kilowatt
for generation and conservation tell one nothing about the true economics
of the different options. One must look at whole systems.
J A Feather London
Letter: Snake wind-up
Blimey – that was a close one. A glimpse at your headline ‘Killer snakes
off Britain’s shores?’ (10 November) had me peering round corners, sleeping
with the light on and expecting hordes of deadly serpents to come hurtling
into the nearby bay at any minute.
But hang on .. the nearest one appears to be about 6,000 miles away,
they do not actually survive under 18 degrees centigrade (no problem with
that here) and as far as we know, they have not yet sussed out the Panama
Canal.
Are the sea snakes coming? Should I phone the authorities? Well, no;
evidently not.
Kathryn Hubbard Burra Isle Shetland
Letter: Snake wind-up
I am a 17-year-old studying biology A-level, and found the article on
sea snakes both enjoyable and thought provoking. However, the diagrammatic
representation of a mammalian heart left me confused: your diagram is surely
incorrect. Deoxygenated blood travels from body tissues to the right atrium,
then right ventricle, before being oxygenated by the lungs. It is then channelled
into the left atrium, then left ventricle (the largest and most powerful
part of the heart), before completing another circuit.
Philip Buckley Northwich Cheshire
Letter: Growing places
In ‘Scratching the surface of evolution’, the authors made a comment
that is incorrect (10 November). They said that plants of the family Moraceae
do not grow in savanna woodland areas. The point is of some importance,
for the fruits of the tropical fig trees must have played an important part
in the evolution of many groups of animals.
I cannot speak of the New World, but in Asia and Africa most species
of Ficus are either at forest edges or are riverine (either within a forest
or outside). Only a small proportion are either rainforest canopy trees,
or understorey shrubs. For example, most banyans (Ficus subgenus Urostigma)
grow at the edges of forests, or on river banks, and in other open areas
in the tropics. In Uganda and Kenya the banyans Ficus brachypoda and F natalensis
typically grow in savanna/woodland.
Dennis Hill Skegness Lincolnshire
Letter: Retirement value
In response to Mike Simpson’s comment on my letter, he is not alone
in having misinterpreted the main thrust of my proposal (Letters, 24 November).
I have no desire to take on anything like the involvement and commitment
in terms of time or travel that full-time research or consultancy entail.
Retired people, like myself, who seek a strictly limited commitment, constitute
a largely untapped source of expertise that could be applied to work that
might otherwise not get done.
Admittedly, the possibility of competing with consultants would have
to be watched and avoided. If ever I have been required to do the same kind
of work as a professional consultant I have always charged, and always will
charge, the going rate, but I have in mind work that these would not normally
undertake, because of the smallness of the projects or because of the absence
of sufficiently satisfying financial rewards.
Simpson’s advice that I form a consultancy company shows how little
he has understood my proposal. Even if I wished to I have nothing like the
resources necessary for such an undertaking. Finally, I dare say I have
as many interests as the next person, and I do not need to be told ‘to get
a nice hobby’ – even this can be expensive. Perhaps when Simpson reaches
my age he might begin to understand the frustration that some of us feel
when we find our expertise, built up over several decades, is no longer
valued.
George Matthews Wadebridge Cornwall
Letter: Retirement value
I am prepared to give some of my time to help compile a list of retired
scientists and technologists, and mix and match with a database of employers
and educational authorities. Opportunistic? Well, why not. Anyone wishing
to participate should contact me at the address below and we will see what
a little bit of mutual self-help can do.
John Henney Business Concern 48 Framfield Road, Uckfield East Sussex
TN22 5AG
Letter: Flock law
Those who seek to establish the reality of ‘sixth senses’ may need to
look no further than birds. I have often noticed, when watching films of
huge flocks of birds, that a sudden change of direction does not seem to
propagate through the flock, but rather to happen simultaneously, sometimes
over hundreds of metres. If this is not telepathy, then what is it?
D T Hall Birmingham
Letter: Practical maths
Daphne Jackson’s report on the teaching of mathematics left me feeling
that she seems to have put aside the case of students with lower ability
(Talking Point, 17 November). She starts off by telling us that ‘pupils
of all abilities’ need opportunities to show what they are capable of; but
in her proposed solutions, it is the ‘able’ students that are catered for.
Also, although reducing the number of different syllabuses will bring
about uniformity, it will breed resentment in a teaching profession that
likes to have the choice of what it teaches our future mathematicians.
In addition, if there is to be coursework in the GCSE maths examinations,
there should be greater options for the students to choose from. Speaking
to many GCSE students, I find that they are bored with doing projects on
such trivial and simple matters, such as finding ‘the area used for advertising
in several different newspapers’. Although these projects should be kept
for the less able students, a graduated level of project difficulty should
be available to cover all student abilities.
I feel that Jackson provides another example of how boards like SEAC
are bringing in theoretical, rather than practical schemes to our education
system.
Mark Stevenson Bishop’s Stortford Hertfordshire
Letter: Nut case
I would like to point out that the nut of the coconut is used for food
and confectionery, and the husk for matting and floor scrubbers, not the
other way round as in ‘Fungus defeats ravenous rhinoceros beetle’ (Science,
10 November). I would like to meet anyone who is able to eat the husk.
Socorro Parco Murdoch University Western Australia
Letter: Weeding out callers
The technology Jeff Hecht dreams about is here in Canada – and may be
in the US – too (‘Another wrong number’, Forum, 20 October). Try this for
peaceful nights: for $3 a month a single phone line can have two numbers
(one listed, the other private) with distinct ‘rings’. A separator box,
costing $150, recognises these rings and directs calls for the listed number
to an answering machine. For another $2 a month, ‘call forwarding’ can divert
daytime calls from the listed number to the unlisted one without divulging
the secret. At night, with forwarding disabled, only close friends can reach
you.
Alan Chattaway Vancouver, Canada